I am a complete noob to macs but have been given an old a1225 - 24" 2007. When starting it displays a white screen with a folder and imbedded '?'. I searched the forums and replaced the disk with a 256gb DSD and upgraded the memory from 2x 1gb to 2x 2gb. I have created a number of snow leopard install dvd disks on my PC which seem to be recognized - lots of disk activity. When I start the mac with the DVD loaded I still get a "?" after 1 or 2 minutes. I have tried numerous start up options including reset nvram, using an external USB DVD drive, and hardware diagnostics. Occasionally I get a white screen with mouse. Nothing I do seems to make any difference. Is there anything else I can try or is the machine past its used by date? --- Post Merged, Feb 9, 2018 --- Just saw a post referencing the status LEDs on the logic board. I'll open the Mac and give an update on their settings.